Synthesis, Structure and Magnetic Properties of a μ‐Carboxylato‐Bridged Ferromagnetic Trinuclear Copper(II) Complex with Lariat Tetraazacrown Ether as Ligand

Abstract

Four o‐toluic acid pendant groups have been attached to a tetraaza crown ether to prepare the novel tetraazamacrocyclic ligand H4L, 4,7,13,16‐tetrakis(2‐carboxybenzyl)‐1,10‐dioxa‐4,7,13,16‐tetraazacyclooctadecane. The trinuclear copper(II) complex of the ligand, [Cu3L·2H2O]2+·2NO3−·2H2O, has been newly synthesized, and its subsequent structural characterization has revealed that it consists of three CuII cores with a isosceles triangular array and that there is a twofold rotation axis that passes through the Cu2 center. The complex contains two symmetry‐related CuN2O3 cores in a distorted square‐pyramidal geometry and one CuO4 core in a distorted square‐plane geometry. The two μ‐bidentate syn‐anti carboxylate groups bridge Cu1 with Cu2, and Cu1A with Cu2. The trinuclear copper(II) complex units are connected in a one‐dimensional zigzag chain via μ‐H2O−NO3−‐bridged hydrogen bonds. Variable‐temperature susceptibility measurements (2−300 K) reveal a ferromagnetic coupling, Ja = 8.08 cm−1, between the μ‐carboxylato‐bridged Cu1 and Cu2, or Cu1A and Cu2, and a weak antiferromagnetic interaction, Jb = −0.40 cm−1, between Cu1 and Cu1A. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Ferromagnetic linear trinuclear copper (II) complex bridged by sulfosalicylate ligand

“…The equatorial plane around central Cu2 is nearly perpendicular to the basal plane of the two terminal Cu(II) ions, which provides a favorable orientation for the orthogonality of the magnetic orbitals, thus causes a dominant ferromagnetic interaction. The value of the magnetic coupling is within those observed in the copper complexes [12,14,15] with bridging syn-anti carboxylate groups (0.37-12.4 cm À1 ).…”

Synthesis, structure, magnetism, and hydrolase and catecholase activity of a new trinuclear copper(II) complex

“…Yield: 3.50 g (60%). 1 To a yellow methanolic solution (20 mL) of 0.28 g of the ligand H 3 L-2pyald (0.5 mmol), 0.30 g of Cu(OAc) 2 ÁH 2 O (1.5 mmol) previously dissolved in 10 mL of methanol was added dropwise, under stirring and the color immediately turned to dark green. Sodium perchlorate (1.5 mmol) was then added to the reaction mixture and after cooling the solution to room temperature a green microcrystalline precipitate was formed which was filtered off.…”

“…In this paper we report the synthesis of the new multidentate N,O-donor ligand H 3 L_2pyald = (N,N 0 -bis-(2-pyridylmethyl)-(2-hydroxy-3-carbonyl-5-methylbenzyl)-1,3-propanediamine-2-ol) and its first trinuclear copper(II) complex, [Cu 3 (L_2pyald)(l-OAc)](ClO 4 ) 2 (1). The structure of 1 was determined by X-ray crystallography and variable-temperature magnetic data in the temperature range of 4-300 K indicate weak antiferromagnetism (J 1,2 ffi À1.0 cm À1 ) between the Cu(1) and Cu (2) centers bridged by the l-alkoxo and l-acetate groups and weak ferromagnetic coupling (J 1,3 = J 2,3 ffi + 4.0 cm À1 ) involving the {Cu(1)(l-phenoxo)Cu(3)} and {Cu(2)(l-phenoxo)Cu(3)} structural units.…”

“…Multimetallic complexes are of great interest due to the special chemical and physical properties that result from the mutual interaction of two or more metal centers [1].…”

Syntheses, crystal structures and properties of two Mn(II) complexes of DTPA-bisamide derivative

“…The intra-chain distance of Mn3Á Á ÁMn4 bridged by the ligand is 19.038 Å , while the shortest inter-chain Mn3Á Á ÁMn3 i (i = x À 1, y, z) and Mn3Á Á ÁMn4 ii (ii = x À 1, y, z + 1) separations are 11.911 and 7.079 Å , respectively. Some polynuclear transition metal complexes often show interesting magnetic interactions [13][14][15]. The short distances of Mn(II) ions in 2 show that it may have interesting magnetic property.…”